1. Field of Art
This application relates to remotely operated devices for the cleaning of the interior surfaces of enclosed spaces, such as storage tanks, via water or other fluid streams directed at the surface. With further particularity, this invention relates to a remotely operated apparatus especially suitable for the cleaning of storage tanks within vessels, such as ships, boats, and barges, the apparatus requiring limited human entry into the enclosed space in order to efficiently carry out the cleaning.
2. Related Art
There have been many efforts to develop semi- or fully automated cleaning devices for the cleaning of surfaces. Non-enclosed surfaces, such as flooring in a large warehouse, driveways, etc. pose no particular problem, as personnel can with relative ease and safety use a conventional hose and nozzle to direct a stream of water or other fluid onto the surface. Other applications may utilize high volume and/or pressure “pressure washers,” but the task still presents relatively few issues when non-enclosed spaces are involved.
Much more significant issues arise in the cleaning of enclosed spaces or areas. Personnel entry into such enclosed spaces can be difficult, with ingress and egress often confined to relatively small hatches through which personnel and equipment must pass, often multiple times. Of much more importance are the significant safety issues which are well known in the industry to be associated with work in enclosed spaces; for example, safety issues associated with maintenance of a safe breathing environment. While various devices and procedures have been developed to address such issues, such as various breathing apparatus and the like, there remain significant hazards associated with enclosed space work.
While there are many settings in which enclosed space work arise, one common one is associated with tanks which are present on vessels used in marine service, such as boats, ships, and barges. Such tanks are usually within the “body” of the vessel, and often are used to carry different fluids from time to time; therefore, it is important to clean the interior surfaces of the tanks between uses. While not limiting the scope of the present invention, it is convenient to address the present invention in the context of the cleaning of tanks on vessels used in support of the offshore oil and gas industry, in the Gulf of Mexico and elsewhere.
Supply boats are frequently used to transport drilling mud and other products to offshore drilling rigs, in support of oilfield drilling programs associated with offshore developments. The mud holding tanks in these boats vary in size. The average size tank is generally rectangular, on the order of 15 feet by 20 feet, with corrugated walls and a wall height of twelve to fifteen feet. Some of the newer boats have round, horizontal tanks.
When drilling mud is shipped to and from the rig, some of the solids in the mud often settle out onto the floor and walls of the tanks. As a result, the tanks require interior cleaning when the boat goes off charter or when a different type of mud is to be carried in the tank.
Current methods of cleaning involve a manned entry into the tank, in order that one or more personnel can manually wash the solids from the interior surfaces out using hoses and pumps (often fire hoses fed by pneumatic diaphragm pumps). The personnel manipulate the hoses and nozzles so as to follow a desired pattern of cleaning the floor and walls of the tank. While the pattern will vary according to the degree of cleaning needed, the volume of fluid being provided for the cleaning function, etc., generally the cleaning pattern involves sequential spraying of the dirty surfaces and “pushing” (via the high pressure/volume fluid stream) the solids and contaminated cleaning fluid to one or more collection points, to suction the solids/liquids from the tank. It can be readily appreciated that for greatest efficiency, any automated system would, to the extent practicable, mimic the cleaning pattern that a person could implement.
As described above, and as can easily be understood, methods involving personnel entry into the tank are a concern to the industry due to the risk exposure and the production limitations put on the workers in the tank. The primary risk to the personnel in the tank arises out of the unsafe conditions of the inside of the typical tank on a vessel. The majority of the mud tanks have a metal, sloped floor that is covered with relatively slippery materials. The personnel are required to wear rubber boots that add to the slippery nature of the floor conditions, and in the typical scenario are required to wash the interior surfaces using a water pressured nozzle to push the solids, etc. mud to a suction hose. Additionally, the personnel are required to wear a breathing air mask with air supply attached thereto, a harness and rubber suit.
In short, these safety requirements and unsafe conditions are a great concern to the industry and need exists for improved apparatus and method for automation of cleaning of interior tank surfaces.